textproduct: Rapid City

KEY MESSAGES

- Hot today and Monday with elevated to near critical fire weather conditions.

- A marginal to slight risk (1-2 out of 5) of severe thunderstorms later this afternoon/evening.

- Slightly cooler conditions return middle of next week.

UPDATE

Issued at 945 PM MDT Sat Jul 18 2026

No big changes were made in the forecast. Still expecting the upper level flow to shift to a more westerly flow, which opens the door for thunderstorms in the area.

The lingering leftover rain showers that are tracking through northwest SD this evening will continue to track east while diminishing overnight. After that, eyes will be on the passing front that could get the next round of storms going tomorrow. Hi- res models and the EURO ENS initiate more thunderstorms tomorrow (Sunday) afternoon, although there is some evidence of storm initiation over the Black Hills by midday. Once storms initiate, they'll track east-to-southeast through the evening.

Some of those storms could be strong to severe. Machine learning ensemble models put a lean towards strong winds as the main concern for severe weather in the South Dakota Plains. Both these machine learning severe weather models and the SPC put a Marginal (level 1 of 5) risk of severe weather over the South Dakota plains tomorrow.

Beyond that, the next round for passing storms will be on Tuesday night into Wednesday.

Temperatures will take a bit of dip midweek as well with highs a little closer to normal, in the 80s to near 90 Tuesday, Wednesday and Thursday. The hotter 90s to low 100s return for the weekend.

DISCUSSION

(This Evening Through Saturday) Issued at 1254 PM MDT Sat Jul 18 2026

Upper ridging continues the western CONUS, with several upper waves approaching the region from the west/southwest. Surface obs show temps have been lagging in the 70s and 80s, but are now rising quickly since the low clouds dissipated. Dewpoints are still well into the 60s across western SD within deep southeasterly flow. Have dropped max temps today to the low to mid 90s across most locations. Still looking at some afternoon and evening storms today. SBCAPE of ~1200 J/kg is expected within the corridor from SCentral SD through the Black Hills into parts of NE WY/NW SD. The next wave is approaching from NCentral and will cross NE WY/NW SD this evening. Shear is strongest across NW SD, where southeasterly low level winds are strongest. Storms are expected to initiate across the Black Hills this afternoon...then NE WY/SE MT in the late afternoon/early evening. As storms track into NW SD just north of the Black Hills, could see a storm or two with gusty winds/hail. These storms will continue eastward toward a less favorable environment over NCentral SD, where both instability and shear weaken. The thermal ridge over the central/northern Rockies will slide eastward overnight tonight toward the CWA, bringing back very hot temperatures. Highs on Sunday will be in the triple digits. Dewpoints will be more reasonable (50s) but will still result in advisory threshold heat index. Will not make any changes to heat-related headlines. A cold front will cross MT and push into ND late Sunday, which will result in strong/severe storms over those areas. By the time the front gets to NW SD, it seems to stall before resurging southward early Monday morning. Still unclear with the severe weather threat Sunday afternoon. It appears the bulk of severe storms will be north and east of the CWA. Good instability and somewhat decent shear will be present, but the forcing with the frontal boundary might be missing. Regardless, could still see convection develop from transient outflow boundaries or orographically from the Black Hills and Bighorns. Any storms that develop may be severe, but think better organization will be limited to areas east of the CWA where increased forcing/shear will be present. Cooler Canadian high pressure will build across the northern Plains for the first half of the week. Uncertain about max temps Monday behind the cold front, which does seem to struggle pushing out the very warm H85 temps. Could still be a hot day on Monday, but wouldn't be surprised if it ends up being a tad cooler than what the NBM shows. Better cold air advection is expected Monday night into Tuesday should bring lower temps...but we'll likely still see highs in the upper 80s to lower 90s. Better chances for precip are expected for the second half of next week.

AVIATION

(For the 18Z TAFS Through 18Z Monday) Issued At 1118 AM MDT Sun Jul 19 2026

Isolated/scattered thunderstorms with local IFR conditions and strong, gusty erratic winds are expected this afternoon and evening. Areas of smoke will push into the area after midnight tonight behind a cold front. The smoke will continue through the day Monday before exiting Monday night.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Heat Advisory until 9 PM MDT /10 PM CDT/ this evening for SDZ001- 002-012>014-025>027-030>032-041>044-046-047-049-072>078. WY...Heat Advisory until 9 PM MDT this evening for WYZ054>056-058>060.